Depolarizer for primary batteries



Patented Apr. 12 1927.

UNITED STATES PATENT OFFICE- GEORGE W. ARMSTRONG, OF FREMONT, OHIO,ASSIGNOR TO NATIONAL CARBON COM- PANY, INC, A CORPORATION OF NEW YORK. I

DEPOLARIZER FOR PRIMARY BATTERIES.

No Drawing.

This invention relates to improvements in sulfur-containing copper oXiddepolarizers for electric batteries, and particularly for batteriescomposed of cells having a caustic alkali electrolyte.

It is known from the disclosure of United States Patent, 1,282,057granted to R. IV. Erwin on Oct. 22, 1918, that the addition of sulfur tocopper oxid depolarizers results in a material increase in the voltageand service life of. cells in which such depolarizers are used. Themethod heretofore used for incorporating sulfur with the copper oxidconsists in mixing the required amount of dry sulfur flour with the oxidand then heating the mixture up to the softening or melting point of thesulfur.

My investigations lead me to believe that the above described method ofsulphurizing results in the formation in the depolarizer of aconsiderable proportion of water-soluble sulphur compounds. Bythoroughly washing sulphurized depolarizer I have been able to removefrom it a variety of soluble sulphur compounds. The presence of suchwater-soluble sulphur compounds has been found under certainconditionsto de detrimental to the operation of cells made up with depola-rizerscontaining them. Their elimination by washing eliminates the detrimentaleifects alluded to above. I prefer, however, to prevent the formation ofsuch soluble sulphur compounds, rather than to remove those which havebeen formed, and I find that it is difiicult to avoid the formation ofthe soluble compounds if the known method of sulphurizing is used.

My improved copper oxide depolarizer is characterized by the presence ofa relatively small proportion of sulphur chemically combined. with thecopper oxide and by substantial absence of sulphur-containing compoundssoluble in the electrolyte.

My preferred method for incorporating sulfur with copper oxid in theinsoluble form consists in agitating cupric oxid while passing incontact therewith a regulated flow of hydrogen sulfid gas. The flow ofgas is controlled so as to prevent too great an evolution of heat, andis shut ofi when the amount of sulfur combined with the oxid reaches thedesired amount. The best results have been obtained when the sulfurcontent was approximately 5%. However, it is to be understood that myinvention is Serial No. 12,453.

not limited to this precise proportion since the sulfur content may bevaried considerably from this proportion so long as all of the sulfur ispresent in a form insoluble in the electrolyte.

The temperature at which the sulfurizing is carried on should be as lowas possible, although a satisfactory product may be obtained' anywherewithin the range from approximately 0 C. to 100 C. 7

My improved depolarizer material may also be prepared by sulfurizing inthe usual way, or by treating with hydrogen sulfid gas in excess, andthen washing out the soluble sulfur compounds with hot water or othersolvents. The washed material is found to possess properties similar tothose possessed by the material prepared by my preferred method abovedescribed.

The improved depolarizer material may also be with othersulfur-containing gases than hydrogen sulfid. For example, sulfur dioxidmay be employed. An aqueous solution of hydrogen sulfid has also beenfound effective.

Cells embodying my new depolarizer have been operated under conditionssimulating those met with in actual signal operation over a period ofsix months and have shown throughout this period a voltage substan-.

tially greater than that shown by high voltage cells embodying the olderkind of depolarizer and operated under the same conditions. The contrastwas particularly marked during the early part of the test.

The superiority of the new depolarizer with respect to length of serviceand regularity of performance is particularly marked when cells in whichit is used are operated under low temperature conditions.

Cells embodying my new depolarizer have shown marked improvement withrespect to corrosion of the zinc plates, and are thus characterized bylong service life.

Having described my invention what I claim is:

l. A depolarizing substance for electric batteries comprising copperoxid and sulfur combined therewith in a form insoluble in theelectrolyte, said substance being substantially free from sulfurcompounds soluble in the electrolyte.

2. A depolarizing substance for electric batteries comprising copperoXid and apprepared by treating copper oxid.

proximately 0.5% sullur tfilll lllltltl therewith in a torn: insolublein the electrolyte, said substance being substantially free from sul lurcon'ipounds soluble in the electrolyte.

3. In a primary battery with alkaline electrolyte, a negative elementcomprising copper oxid and sulfur combined therewith in a form insolublein the electrolyte, said element being substantially free from snl'l'nrcompouiulssoluble in the electrolyte.

l. in a primary battery with alkaline electrolyte. a negative elementcomprising cop per oxid and approximately 0.5% sulfur combined therewithin a form insoluble in the electrolvte said element being substantiallyfree from sulfur compounds soluble In the electrolyte.

5. In a primary battery, an alkaline electrolyte. a zinc electrode and anegative elenient C(JllllJllSlllg copper oxide and sulfur coniliiinedtherewith in a form insoluble in the electrolyte, said element beingsubstantially free. :Eroinsultur compounds soluble in the electrolyte.

(3. A process of pre hiring a depolarizer for electric batteries, whichconsists in treating copper oxid with a sulfur-containing gas in suchamount and under such temperature conditions that substantially all ofthe sulfur combined with the copper oxid in a form insoluble in analkaline electrolyte.

7. A process of preparing a clepolarizer for electric batteries, whichconsists in treating copper oxid with hydrogen sulfid in such amount andunder such temperature conditions that substantially all of the sulfuris combined with the copper oxid in a form insoluble in an alkalineelectrolyte.

8. A, process oil preparing a depolarizer for electric batteries, whichcomprises incorporating with copper oxitl sulfur in a form insoluble inan alkaline electrolyte and eliminating any soluble sulfur compoundswhich may be present.

In testimon whereof, I aflix my signatnre.

( 1 X )R( l E \V. ARMSTRONG.

